Refactoring ideas

[DeD1rk]

This issue lists some proposed ideas for refactoring:

• Make AuthBloc a cubit.
• Make ThemeBloc a cubit.
• Combine RegistrationsCubit into EventCubit.
• Create a Page subclass for each screen, that specifies the name, arguments and optionally transition animations.
• Replace ApiException enum by a class(-tree) that may contain a string.
• Move expensive JSON parsing into isolates.
• Move the CalendarCubit's expensive operations into isolates.
• Simplify exception handling in ApiRepository.
• Outline url handling to a utility function (mainly HtmlWidget.onTapUrl)
• Change to StatelessWidget wherever possible
• Make a common qubit for liststates since most of the code can be almost identical #444
• Use typed routes where possible

These may not all be useful or necessary.

[se-bastiaan]

• Use classes for all SearchDelegate implementations to prevent code duplication

[DeD1rk]

• Use classes for all SearchDelegate implementations to prevent code duplication
  Good one